Bug Drag & Drop sends Editor Panels & Windows flying

When I use the mouse to move editor panels and windows around, they fly away at warp speed.

Specifically, it looks like the relative position to the mouse is calculated wrongly, causing whatever is being dragged to move to one side, then twice as far to the other side in rapid succession:

https://imgur.com/a/NiyBSRr

Could be a regression from the old mouse bug that was present in 5.3 but got fixed in 5.6.

 

Similar to the second video by kodenkm?
https://forum.unity.com/threads/unity-2018-2-2f1-child-window-resizing-issue.535319/#post-3591669

I've got this issue as well. Unity 2018.2.16f1

 

I think kodenkm's issue is probably a different one.

Those are system windows (they have a frame with standard minimize/maximize/close buttons). For me, only the editor panels (made with Unity's own UI system) show weird behavior, real windows behave correctly.

 

The second video? We are talking about this video, right?

This is especially an issue for me when trying to place the Shader Graph window.